Blade with Side Teeth for Opening/Holding/Closing Pleated Bags and Method for Opening/Closing the Mouth of Bags by Means of Said Blade

ABSTRACT

Blade for opening bags ( 1;2 ) with pleats ( 1   a,   2   a ), comprising a flat body ( 10 ) with a bottom edge ( 11 ) and a top part ( 12 ) suitable for stable engagement with associated operating means, and a tooth ( 20 ) substantially extending in the vertical direction (Z-Z) and connected to the body ( 10 ) along the top edge ( 10   c ) of each lateral side ( 10   b ) of the body ( 10 ), a cavity ( 22 ) which extends in the vertical direction (Z-Z) and is of suitable width in the longitudinal direction (X-X) being formed between each tooth ( 20 ) and the corresponding side ( 10   b ).

The present invention relates to a blade with side teeth for opening/holding/closing the mouth of pleated bags and a method for opening/holding/closing the mouth of pleated bags by means of pairs of said blade.

It is known, in the technical sector relating to the filling of bags with loose products by means of automatic machines, that there exists the need to fill preformed bags of varying shape and size which are opened in the region of the mouth by means of special suckers and shaped plates inserted into the mouth itself, filled and closed at respective stations of said machines to where the bags are conveyed are by means of suitable conveying devices.

It is also known that, with the use of the known bag opening plates, the operation of closing the mouth of the bags is particularly difficult in the case of so-called “pleated” bags, i.e. those bags which have lateral flanks with an inward fold so as to form a pleat, said pleat remaining closed with predefined folding lines during formation and, instead, being widened at the bottom, so as to disappear, following filling of the bag whose continuous flank it forms.

This deformation of the pleat, however, must not occur at the mouth of the bag which, once filling has been completed, must be closed and retain the original folding lines, in order to prevent false folds which could result in imperfect closing actions and/or points which are not sealed and which may allow air to enter and/or the product to escape, as well as unattractive false folds which may be interpreted as closing defects by the end user.

A further example of the prior art according to the preamble of claim 1 is described in U.S. Pat. No. 7,407,139 which relates to an elastically deformable blade not suitable for use as bag opening element in automatic bag filling and sealing machines.

The technical problem which is posed, therefore, is to provide means suitable for performing the opening of the mouth of a bag along predefined folding lines of associated lateral pleats and keeping the folds along said predefined lines also during filling and subsequent closing of the bag mouth so as to provide a solution to the abovementioned drawbacks of the prior art.

In connection with this problem it is also required that this device should have small dimensions, be easy and inexpensive to produce and assemble and be able to applied easily also to already existing machines in order to reduce the downtime due to changes in format.

These results are achieved according to the present invention by a blade for opening pleated bags, comprising a flat body with a bottom edge and a top part suitable for stable engagement with operating means, and a tooth substantially extending in the vertical direction Z-Z and connected to the body of the blade along the top edge of each lateral side of the said body, whereby a cavity extending in the vertical direction Z-Z and of suitable width in the longitudinal direction X-X is formed between each tooth and the corresponding side.

The present invention also relates to a method according to the characteristic features of claim 11.

Further details may be obtained from the following description of a non-limiting example of embodiment of the subject of the present invention provided with reference to the accompanying drawings in which:

FIG. 1: shows a perspective view of a blade according to the present invention;

FIG. 2: shows a front view of the blade according to FIG. 1;

FIG. 3: shows a schematic cross-section along the plane indicated by the line III-III in FIG. 2;

FIG. 4: shows a cross-section along the plane indicated by the line IV-IV in FIG. 3;

FIG. 5: shows a partial front view of a second embodiment of a blade according to the present invention;

FIG. 6: shows a perspective view of the blades during insertion into the mouth of a bag;

FIGS. 7 a-7 c show cross-sectional views of the bag and the blades during the blade insertion, and mouth opening and closing operations; and

FIG. 8: shows partial perspective views of the sides of bags with two different types of pleat.

As shown in FIG. 1 and assuming solely for the sake of simplification of the description and without any limitation meaning a set of three reference axes in a longitudinal direction X-X, transverse direction Y-Y and vertical direction Z-Z, respectively, as well as a bottom part corresponding to the part for entry into the bag and a top part opposite to the bottom part, the blade according to the present invention for opening the mouth 1 a, 2 a of bags 1,2 with a lateral pleat 1 b, 2 b essentially comprises a flat body 10 with a bottom edge 11 and top part 12 suitably shaped for stable engagement with operating means, not shown, incorporated in conventional filling machines schematically indicated by M.

The blade is flat and rigid in order to prevent elastic deformations in the transverse direction Y-Y.

According to a preferred embodiment the bottom edge of the body 10 has opposite ends in the longitudinal direction X-X with a respective rounded part 11 a suitable for facilitating the entry of the blade into the mouth 1 a, 2 a of a bag 1,2.

According to the invention, along the opposite lateral sides 10 b of the body 10, the blade has a tooth 20 substantially extending in the vertical direction Z-Z and connected to the said body 10 along its top edge 10 c so as to form a cavity 22 of suitable width in the longitudinal direction X-X and depth in the vertical direction Z-Z.

According to preferred embodiments the tooth 20 has a tip 23 with a rounded inner edge 23 a situated substantially opposite the rounded part 11 a of the edge 11 of the body 10 so as to define a widening 22 a in the longitudinal direction X-X of the cavity 22, suitable for favouring the entry of the blade into the bag.

The outer front surface of the tooth 20 also has vertical grooves 21 designed to form corresponding reliefs 21 a; in this way and as shown in FIGS. 3 and 4, the surface 10 a of the body 10 is set back at a suitable distance D from the plane 20 a passing through the peaks of the reliefs 21 a so as to favour gripping of the bag, as will emerge more clearly below.

As shown in FIG. 5, it is also envisaged that the tooth 120 may be mounted on the body 10 of the blade by means of a suitable connecting bracket 121; in this case the tooth 120 is shaped in the manner of an “overturned U” with two vertical sections 120 a and 120 b and a horizontal section 120 c; the tooth 120 of the overturned U is associated with screw means 122 able to co-operate with the horizontal section 120 c of the U so as to form a hinging axis about which the U is able to rotate; in this way the first vertical section 120 a forming the tooth for engagement with the portion of the pleat may be inserted with ample play which is taken up with closing of the jaws 32 which encounter the second vertical arm 120 b on the outside of the pleat and, pushing it in the transverse direction, force the tooth 120 to rotate about the axis of rotation and position precisely the vertical section 120 a in contact with the portion of the pleat for firm gripping.

As indicated by the broken in the figures, it is also envisaged that, in order to facilitate entry of the blade into the mouth of the bag, the body 10 of the blade has a perimetral edge provided with a chamfer 111 a on the outside.

Owing to the blade structure described above it has been possible to develop also an associated method for correct opening/closing/sealing of the mouth of pleated bags, said method, with reference to FIGS. 6 and 7, comprising the following steps:

-   -   preparing a pair of blades 10, each of which is fastened to a         respective operating means forming part of a filling machine         schematically indicated by M (FIG. 6);     -   transporting the bag 1,2 with associated pleat 1 b, 2 b already         formed along associated folding lines 1 c, underneath the blades         10;     -   partially opening the mouth 1 a, 2 a of the bag, for example         using suction-cup means;     -   inserting the blades 10 in the vertical direction Z-Z inside the         mouth 1 a, 2 a of the bag 1,2, keeping the teeth 20 outside the         mouth itself and inside the portions ld of the pleat 1 b, 2 b         (FIGS. 6,7);     -   closing in the transverse direction suitable jaws of a gripper         operated by the machine M around the outer surfaces of the bag         1,2;     -   simultaneously holding in the transverse direction Y-Y the mouth         of the bag by means of closing of the jaws 32 so as to position         the central section thereof against the inner blade 10 and the         opposite ends 32 a of the jaws 32 against the portions 1 d of         the pleat 1 b, 2 b (FIG. 7 b), in such a way that the jaws 32         rest against the surface 10 a of the body 10 inside the bag and         the surface 21 a of the peaks 21 of the tooth 20 outside the         bag, ensuring firm gripping both of the bag mouth and the outer         edges of the pleats along the folding lines 1 c of the latter         (FIG. 7 b);     -   holding said portions ld of the pleats against the respective         teeth 20 during all the working steps;     -   relative opening of the blades 10 and the jaws 32 in the         transverse direction;     -   filling the bag with the product;     -   return movement, in the transverse direction Y-Y of the blades         and the jaws into the initial closed position of the mouth and         simultaneous closing, in the longitudinal direction X-X, of         flanges 31 situated opposite the sides of the bag and forming         part of the machine M;     -   inserting the said flanges 31 inside the respective pleat 1 b, 2         b so as to interfere with the folding line if inside the pleat 1         b, 2 b itself and restore alignment of the closed pleat with the         bag mouth (FIG. 7 b);     -   releasing the bag, transporting the bag to the sealing station         and sealing.

It is therefore clear how the blade according to the invention allows easy, precise and repeatable entry into the mouth of the bag, ensuring at the same time that the original folding lines of the pleat of the bag are maintained, said lines being firmly held and kept precisely in their correct position on the bag mouth, during all the working steps, resulting in the formation of a package which is precise, symmetrical and without deformations and in particular the correct positioning of the outer ribs in the vicinity of the top part of the pleated bag mouth.

It is also pointed out that the blade according to the invention work in a perfectly efficient manner both in the case of bags 1 with a normal pleat and in the case of bags 2 with pleats formed with the edge 2 g of the respective vertically welded portions 1 d (FIG. 8).

Although described in connection with certain constructional forms and certain preferred examples of embodiment of the invention, it is understood that the scope of protection of the present patent is defined solely by the following claims. 

1. Blade for opening/holding/closing bags (1;2) with pleats (1 b, 2 b), comprising a flat body (10) with bottom edge (11) and top part (12) suitable for stable engagement with operating means (M), characterized in that it is flat and rigid and comprises a tooth (20;120) substantially extending in the vertical direction (Z-Z) and connected to the body (10) at the opposite side ends of the top edge (10 c) of the said body (10) and in that said surface (10) extends with continuity in the longitudinal direction (X-X) along a section such as to define a cavity (22) extending in the vertical direction (Z-Z) and of suitable width in the longitudinal direction (X-X) between each tooth (20;120) and the corresponding side (10 b) of the surface (10) itself.
 2. Blade according to claim 1, characterized in that said tooth (20;120) has a tip (23) with a rounded inner edge (23 a).
 3. Blade according to claim 1, characterized in that the opposite ends of the bottom edge (11) have a respective rounded part (11 a) opposite the tooth (20;120).
 4. Blade according to claim 1, characterized in that the outer front surface of each tooth (20;120) has vertical grooves (21) designed to form corresponding reliefs (21 a).
 5. Blade according to claim 4, characterized in that the surface (10 a) of the body (10) is set back at a suitable distance (D) from the plane passing through the peaks of the reliefs (21 a) of the tooth (20;120).
 6. Blade according to claim 1, characterized in that said tooth (20) is formed as one piece with the blade (10).
 7. Blade according to claim 1, characterized in that said tooth (120) is mounted on the body (10) of the blade by means of a suitable connecting bracket (121).
 8. Blade according to claim 7, characterized in that said tooth (120) is shaped in the manner of an “overturned U” with two vertical sections (120 a, 120 b) and a longitudinal section (120 c).
 9. Blade according to claim 7, characterized in that said tooth (120) comprises screw means (122) able to co-operate with the horizontal section (120 c) of the U so as to form an axis of rotation which is parallel to the vertical direction (Z-Z) and about which the “U” is able to rotate.
 10. Blade according to claim 1, characterized in that the perimetral edge of the body (10) has a chamfer (111 a) on the outside.
 11. Method for opening/holding/closing the mouth (1 a; 2 a) of bags (1;2) with pleats (1 b; 2 b) by means of blades (10) and suitable gripping jaws (32) forming part of a packaging machine (M) and comprising the following steps: preparing a pair of blades (10) each of which is fastened to a respective operating means of the machine (M); transporting the bag (1;2) with pleats (1 b; 2 b) so that its mouth (1 a; 2 a) is situated underneath the blades (10); partially opening the mouth (1 a; 2 a) of the bag; inserting the blades (10) in the vertical direction (Z-Z) inside the mouth (1 a; 2 a) of the bag (1;2); closing in the transverse direction the jaws (32) of the gripper around the outer surfaces of the mouth of the bag (1;2); relative opening of the blades (10) and the jaws (32) in the transverse direction Y-Y; filling the bag with the product; return movement, in the transverse direction Y-Y, of the blades and jaws into the initial closed position of the mouth; symmetrical closing, in the longitudinal direction (X-X), of opposite flanges (31) forming part of the machine (M) so that they are inserted inside the respective pleat and interfere with the folding line (1 f) inside the pleat (1 b, 2 b) itself; characterized in that the blade (10) has teeth (20;120) according to claim 1, said teeth being kept outside the mouth (1 a, 2 a) of the bag and inside the portions (1 d) of the corresponding pleat (1 b, 2 b), and in that closing of the jaws (32) keeps the portions (1 d) of the pleat (1 b; 2 b) against the respective tooth (20;120) during all the operations for opening/filling/closing the bag (1;2).
 12. Method according to claim 11, characterized in that said bag (2) has pleats (2 b) with portions (1 d) formed with a vertical edge (2 g) welded vertically. 